Comparison Of Motor Execution And Motor Imagery Brain Activation Patterns

Motor imagery as a training method or a rehabilitation therapy is widely used in the field of training and clinical treatment. There are a large number of studies have investigated the brain mechanism of motor imagery. However, whether the primary motor cortex is involved in motor imagery is still controversial. Whether brain activation patterns of motor execution and motor imagery were similar, both of them activated the primary motor cortex. In addition, some researchers found that exercise intensity improved the activation levels of brain cortex during motor execution task. And we don’t know how imagination intensity’s effects in motor imagery task on primary motor cortex. Therefore, we explore the relationship between exercise (imagination) intensity and the brain mechanisms during motor execution task or motor imagery task, especially on primary motor cortex.In this study, we used four experiments to explore those question:The first experiment was to compare the brain activation patterns between motor execution and motor imagery. We detected 30 subjects’(15 for male and 15 for female) brain activation patterns in the lifting 4 pounds dumbbell task and the imagery lifting task. And we wanted to find some relationship among the primary motor cortex, the motor imagery task, and the motor execution task. Results showed that activation patterns of the motor imagery were similar with the motor execution’s, whether male or female, in the motor execution task or in the motor imagery task, all of them activated primary motor cortex, premotor and supplementary cortex, primary somatosensory cortex and somatosensory association cortex. And in the motor execution task, all of subjects had shown a lateralization of the left hemisphere, that activation levels of the left hemisphere were higher than the right hemisphere. But in the motor imagery task, the lateralization of brain hemisphere was absent.The second experiment was to investigate the effect of exercise (imagine) intensity on brain activation levels of the motor execution task and the motor imagery task. After controlled some disturbance variables, such as variables of task and subject, we added exercise (imagine) intensity as an operating variable in the second experiment. And the results showed that exercise (imagine) intensity only had an influence on the cortex activation levels during the motor execution task, the exercise (imagine) intensity was stronger and the activation level was higher. But it did not work in the motor imagery task, there were no significant differences in the cortex activation levels under the different imagine intensity’s motor imagery task. Furthermore, no matter in which exercise (imagine) intensity, there were significant differences in the activation strength of cortical under these two task, that activation levels of the motor execution was higher than the motor imagery’s.Due to exercise intensity without effecting on the motor imagery in the second experiment, we guessed the reason maybe that the degree of difference between imagine intensity was less than the exercise intensity, or subjects weren’t able to reach complete relaxation. In order to investigate the authenticity of this conjecture, we conducted the third experiment and the fourth experiment. In the third experiment, we increased the intensity of imagination. And we found that there were significant differences in the primary motor cortex and somatosensory cortex between the higher imagine intensity and the lower imagine intensity. Suggested that imagine intensity can adjust the activation levels of motor cortex related to motor imagery.In fourth experiment, we implemented a real-time neurofeedback system based on fNIRS to confirm the efficacy of fNIRS-mediated neurofeedback technology. And use this method to relax subjects at rest period, to control imagination of subjects during motor imagery. The results showed that real-time fNIRS neurofeedback induced significantly higher activation of the primary motor cortex and somatosensory cortex. These findings suggested the feasibility and efficacy of fNIRS neurofeedback on performance of motor imagery.All above, we could obtain the following conclusions:(1) Brain activations of motor imagery was same as motor execution, both of them basically activated the primary motor cortex, premotor and supplementary cortex, primary somatosensory cortex and somatosensory association cortex.(2) Activation levels of the motor execution was higher than the motor imagery’s, and showed a iateralization of the left hemisphere.(3) exercise intensity effected the activation levels of the primary motor cortex, premotor and supplementary cortex, primary somatosensory cortex and somatosensory association cortex in motor execution task; and imagine intensity effected the activation levels of primary motor cortex and primary somatosensory cortex in motor imagery task.(4) Real-time fNIRS neurofeedback induced significantly higher activation of the primary motor cortex and somatosensory cortex. These findings suggested the feasibility and efficacy of fNIRS neurofeedback on performance of motor imagery.